Electrochemical salvaging method



Feb. 1,0,- 1948., A. J.. Fusco Erm. t 2,435,714

ELECTROCHMICAL SALVAGING METHOD Filed Sept. 28,v 1942 Patented Feb. 10, 1948 ELECTROCHEMICAL SALVAGING METHOD Anthony J. Fusco, Belleville, N. J., and Jerome L. Bleiweis, New York, N. Y., assignors to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application September 28, 1942, Serial No. 453,988

2 claims. l

hole, the shank of the stud will break due to defects in the shank or to the application of excessive leverages to the stud head. The conventional procedures for removing broken parts of tools and studs have not been very effective in precision work, and large quantities of castings containing embedded tools must be scrappedV completely. As these castings are quite often complex and expensive, the loss through scrap ping tends to increase the cost of manufacture and to decrease the production rate of the complete assembly.

It is an object of the present invention to provide a system wherein, by electrochemical processing, parts of embedded metal may be removed from the main body of a casting. a forging or other metal object.

It is another object of the invention to provide an apparatus for removing one metal member from the body of another, which includes means for circulating an electrolyte in the region of the metal to be removed, and making this metal the anode in a circuit which is part of an apparatus for carrying out an electrochemical process.

Other objects of the present invention include the provision of apparatus for continuously circulating a metal solvent through apparatus applied locally for the removal of certain metals vfrom metals of dissimilar basic composition, and

also, the use of an electrochemical method for the removal of certain metal members from bodies of dissimilarmetalllc composition.

Other objects will appear from a study of the following specification when made in conjunction with the attached drawings, throughout which like numerals designate like parts, and wherein the single ligure of the drawing is an arrangement, partly schematic and partly in section, of an electrochemical apparatus of the present invention.

Having particular reference to the drawing, I0 is a casting, forging or other body of aluminum or aluminum alloy having a threaded bore II in which is embedded a shank portion I2 oi a broken steel stud member. v A container I3, which may be a glass funnel, is clamped to a supporting arm I4 carried upon a supporting stand I5, and has a lower throat portion I6 with a smooth open lower edge II in contact with the surface of casting I0 surrounding the bore'l I.

A tubular rod I8 of brass, having a longitudinal bore I9, projects through the container I3 and has its lower end or tip 20 closely adjacent the open end I1 of throat I6. Thempper end of the tube I8 is fixed to an arm member 2I carried by a supporting stand 22. A conduit 23, which may be of rubber or the like, is connected to the top end of tube I8, and extends into the tank or reservoir 24, which contains a liquid 25. A pump 2S is positioned within conduit 23 intermediately of the two ends thereof, and is connected so that it draws liquid from container I3 through bore I9 and into conduit 23, and thus, into reservoir 24. Another conduit 21 is open to tank 24 through port 28, and at its lower end 29, it empties into container I3. A valve 30 is provided in conduit 2'I for regulating flow of liquid through conduit 21.

The foregoing apparatus is described and claimed in the copending divisional application for U. S. patent Serial No. 516,278, iiled December For the removal of steel from aluminum, it has` been found that the electrolyte may be ammonium sulfate ((NHzSOi), and '750 grams per liter of water (H2O) has been found to be a satisfactory concentration for the electrolyte.

Because of the fact that steel stud shank I2 is embedded tightly in bore II of aluminum casting I0, shank I2 and casting Il] are in good electrical contact. The system for removing steel stud I2 from aluminum casting I@ is put into operation upon adjustment of the container I3 into the position indicated, and the lowering of tube I8 into container I3 to the position shown.

The iiow of liquid into container I3 can be adjusted by manipulation of valve 30, and thus, liquid drawn upwardly through bore I9 and into tank 24 will be replaced in container I3 by sumcient liquid flowing from tank 24 into container I3, so that the process may be carried out con tinuously.

With the apparatus positioned as shown, current will be conducted through the liquid 25 between stud shank I2, which is an anode, and tube I8, which is a cathode, and by electrochemical action, the stud shank I2 will be gradually dissolved by the ammonium sulfate, which is being constantly renewed by the action of the suction pump 26 in drawing liquid through rod i8 carrylng away the removed steel. i

The voltage of source 3| should be ashigh asl is practical Without introducing. arcing and flash-over conditions in the apparatus, but for a given voltage, the amount of current drawn by the circuit will depend principally upon the dis# tance between the anode (I2) and the cathode (I8). If the anode and cathode are touching, the current drawn as indicated by ammeter 39 lwill be a maximum, since this is a short circuiting condition. Also, if the anode and cathode are too close, undesired sparking, which will depend upon the value of the voltage chosen for source 3|, will occur. Therefore, the optimum distance between anode I2 and the tip 20 of cathode I8, will be that minimum distance which will not cause sparking between the electrodes or short circuiting. Practice will indicate what `value of current can be used, and as the optimum value decreases, cathode I8 can be either manvually or automatically advanced toward anode I 2 to prevent the current as indicated in ammeter 39 from decreasing to too low a value. Just as the steel shank I2 dissolves completely, the current will decrease to zero, indicating complete removal of the steel. The process is completed upon this condition being attained.

The ammonium sulfate does not attack the aluminum casting I0, and at the end of the elec trochemical process, all the steel will be dissolved and the threads in bore I I will be accurate when gauged.

The above explanation sets forth a means whereby steel tools are removed from aluminum castings. The novel process is applicable also to the removal of steel from magnesium bodies and to the removal of steel from brass, bronze, corrosion-resistant steel and other basic metals. An'electrolyte for the removal of steel from mag.-

nesium may be a solution of hydroiiuoric acid in water (H2O). A 48% solution has been found to operate satisfactorily. In the removal of tool steel from stainless or corrosion-resistant steel, an electrolyte of nitric acid may be used.

. It has been stated above that cathode i8 may be automatically advanced toward the stud shank I2 as the shank is dissolved in order to keep the distance between the anode and cathode constant, and thus, obtain the optimum ow of cur rent through the circuit. In practice, this constant distance may be maintained by mounting `tubular member I 8 so that it may be lowered by pressure imposed, for example, by a weighted member, and by inserting a spacer of an inert material between tip 20 and the top of stud shank .I2. This spacer may be a tubular section of glass or conventional plastic material having notches inthe bottom part to permit the electrolyte to be freely drawn through bore I9 by pump 26.

Only one embodiment of the invention has been shown and described. The invention, however, is not to be limited to the example contained in the description, but solely by the scope of Vthe appended claims.

` What is claimed is:

1. In the salvaging of industrial parts; a method of removing a steel insert from a body of aluminum, which comprises continuously circulating a solution of ammonium sulfate in water in .contactk with the steel insert, and dissolving the steel insert by anodic treatment in the solution.

2. A method of salvaging an article of manufacture formed of aluminum and having a broken tool part embedded therein formed of steel; comprising the steps of supplying a solution 0f ammonium sulfate in water in contact with the embedded part; projecting an electrically conducting member into saio1 electrolyte adjacent the embedded part and in spaced relation thereto; providing an external source of electromo,n tive force; electrically connecting said member and part to said external source of electromotive force so as to negatively charge said member and positively charge said part Vto effect disintegration of said part; circulating the electro.- lyte in the immediate region of the part so as to disassociate therefrom the disintegrated portions of said part and carry said portions away and free from said article; and adjusting said member in relation to said part so as to lmaintain a substantially constant distance between said member andpart.

ANTHONY J. FUSCO. JEROME L. BLE'IWEIS.

REFERENCES CITED The following references are of record in the le or this patent:

UNITED STATES PATENTS Number Name Date 2,156,156 Mahlck Apr. 25, 1939 1,329,315 Weaver Jan. 27, 1920 1,416,929 Bailey May 23, 1922 1,845,052 Laukel Feb. 16, 1982 2,196,133 Webb Apr. 2, 1940 898,404 Edison Sept. 8, 1908 2,157,699 Hardy May 9, 1939 1,319,928 Kennedy Oct. 28, 1919 656,982 Kendall Aug. 28, 1900 2,162,789 Raub June 20, 1939 FOREIGN PATENTS Number Country Date 335,003 Great Britain Sept. 18, 1930 299,298 Great Britain July 22, 1929 482,563 Great Britain lliar. 31, 1938 3,722 Great Britain 1913 315,667 Germany Nov. 10, 1919 OTHER REFERENCES "Zeitschrift fur Metallkunde, vol. 16, .April 1924, pages 132, 133; article b`y Pirani et ai.

The Electrochemical Society, Preprint 81-6, April 20, 1942; article by Loose; page 65.

The Metal Industry, Nov. 12, 1937, pages 485, 486; article by Gardam. 

